According to wikipedia, 'his mystery novels are set in the Four Corners area of New Mexico, Arizona, Colorado and Utah and beyond, sometimes to Washington, DC, Los Angeles and other areas. The protagonists are Joe Leaphorn and Jim Chee of the Navajo tribal police.
Hillerman's writing is noted for the cultural details he provides about his subjects: Hopi, Zuni, European-American, federal agents, and especially Navajo Tribal Police. His works in nonfiction and in fiction reflect his appreciation of the natural wonders of the American Southwest and his appreciation of its people, particularly the Navajo.'
Here are some images of the countryside he writes about.